Thrift Store has some used items and new items also, I heard peoples could land on some treasure item and sell them on ebay for alot of money. You should check our the "flipping" on reddit. They have alot of user that talks about their success at the thrift store hunting and selling them on ebay.
I made 50k+ per year reselling used books on amazon .. you can also sell your collectible books on ebay even if you did this parttime on the side you will net around 10-15k per year so your student loans would be paid off..
I like how people mention stocks but when your broke you need money to invest .. its not that easy and every dollar counts
Another side income is if your handy is promoting painting/pressure washing/repairs etc on craigslist .. cost $5 for the ad but you can build it up with cliente than ad in business cards etc and have a side income with a little handyman business.. its also a very nice earning to pay off debts and all cash money
Refund and SE is where its at when it comes to side hustles. Yes its technically not super safe but if you have good opsec and know what you are doing you can make at least $5k in 2-4 weeks assuming you have a cc with good limits.